Coding apparatus



May 17, 1932,. P. N. BOSSART CODING APPARATUS Filed Oct. 9, 1929 2 Sheets-Sheet 1 INVENTOR P. /V. Bo 3340-1? May 17, 1932- P. N. BOSSART CODING APPARATUS Filed Oct. 9, 1929 2 Sheets-Sheet 2 INVENTOR P, 1V. B a s 5 a Patented my 17,. 1932 UNITED s'ra'res I PATENT OFFICE PAI 'L N. BOSSAR'I, OF SWISSVALE, PENNSYLVAN ASSIGNOR TO THE UNION SWITCH 6'0 SIGNAL COMPANY, OF

SYLVANIA.

SWIBSVALE, EENHSYL'VANIA, A CORPORATION OI PENN- com'no APPARATUS Application fled October 9, 1928. Serial No. 398,842.

two radially extending shoulders 9. and 9 My invention relates to coding apparatus, and particularly to coding apparatus or" the type comprising a contact and means for periodically operating said contact at a con- 6 stant predetermined frequency.

One object of my invention is to provide apparatus of this type which will operate upon a small amount of power.

I will describe several forms of coding a paratus embodying'my invention, and wlll then point out the novel features thereof in claims. r

In the accompanying drawings, Fig. 1 1s a view, partly diagrammatic showing, in isolfl-met'ric projection, one form of coding apparatus embodying my invention arranged toperiodically interrupt the supply of current to a pair of line wires. Fig. 2 is a sectional view showing armature Bin its normal position with respect to the poles of the associated electromagnet A. Fig. 3 is a view similar to Fig. 2 showing the armature B in a deflected position. Figs. 4: and 5 are views similar to Fig. '2 showing modified forms of armature B, and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. l, the coding apparatus, in the form here shown, comprises an oscillatable armature'B controlled by an electromagnet A and arranged to function as a. torsion pendulum. The electromagnet A. comprises a magnetizable core 1 having two spaced poles 1* and 1 and provided with an energizing winding 2. As here shown the winding 2 is made up of two coils connected in series, but this particular construction is not essential. The electromagnct A is mount-v ed upon two brackets 5 ando of nonmagnetizable material, such as brass, the upper ends of which are attached to the poles 1 and i bv means of suitable bolts 7 The armature B is located between the poles 1 and '1 of electromagnet A and, as here sh own, is cylindrical in shape, but is provided with two diametrically opposite symmetrical projections 8* and 8", which co-act with the poles 1 and 1, respectively. The projection 8, as best seen'inFig. 2, is provided with while the projection. 8 is provided with two similar shoulders 9 and 9 The outer surfaces of each of the projections 8 and 8" is substantially arcuate, but a portion of the outer surface of the projection 8 adjacent the shoulder 9 is rounded more abruptly than the remainder of the outer surface of this pro ection while a portion of the outer surface of the projection 8 adjacent the shoulder 9 is similarly rounded. With the-arma-- ture constructed in this manner, if the armature is rotated in a counter-clockwise direction from its normal position, in which it is illustrated in Fig. 2, to the position shown in full lines in Fig. 3, the air gapsbetween the armature and the poles 1 and 1 are gradually decreased, thus gradually decreasing the reluctance of the magnetic circuit includin the armature and the poles 1 and 1", but if the armature is rotated from its normal po sition in a clockwise direction to the position shown in dotted lines in Fig". 3, the air gaps between the armature B and the poles i and 1 are at first gradually and then abruptly increased, thus producing a similar increase in the reluctance of the magnetic circuit including the armature and the poles 1 and 1". The mass or" the armature B is comparatively large, and order to permit the armature to oscillate with a minimum of Eriction, the'weight or the armature is carried by a filament 3 of suitable resilient material such, for example, as a phosphor bronze suspension wire. The lower end of the filament 3 is l astened to the armatureB, and as here shown, the filament extends upwardly with considerable clearance through a hole in an upper pivot 11 attached to the upper side of the armature B, and through two tubes 12 and 1 3 which are screwed respectively into the lower and upper ends of a hole in the core 1 of electromagnet A. The tubes 12 and 13 protect the filament throughout its length. The upper end of the tube 13 is tapered and is threaded on the outside to receive a nut 10 which is similarly tapered and threaded on the inside. The upper end of the tube 13 is also provided with a plurality of longitudinal saw kerfs to form jaws which grip the fila- 'and'it wil beapparent that the length of the filament may be increased or decreased as de- I sired by replacing the tube 13 with a longer or shorter tube so that the filament may be gripped at a eater or'lesser distance from the point at w ich it is fastened to the armature B.

Alignment of the armature B is preserved I by an upper bearing 12" which receives the upper pivot 11 loosely and by a lower bearing 14 which similarly receivesa lower pivot 15 attached to the underside of the armature B. The upper bearing 12' is formed in the lower endof the tube 12 while the lower bearing 14 is formed in abearing block 14 fastened between the brackets 5 and 6 by suitable screws 16, only one of which is shown in the drawings.

Armature B is biased to the normal position in which it is illustrated in Fig. 2 by the filament 3, a spiral spring 24, and by res1 l- 'ient contact fingers, here shown as two in number and designated 18 and 21. One end of the spiral spring 24 is fastened by means of a screw 23 to he lower pivot 15, whlle the other end of the \spiral spring 24 is fastened to the upwardly extending arm 25' of a supporting member 25 by means of a clamp 25.

orting member 25 1s fastened between the brackets 5 and 6 by means of screws 26 which pass through elongated slots 27 in these brackets. The elongated slots 27 permit 'novement of the supporting member 25 toward and away from the pivot 15, thereby permitting adjustments in the efiective len h of the spring 24 without producing a side thrust on the armature.

The contact fingers 18 and 21 areof some resilient electrical conducting materlal such for example, as phosphor, bronze, and are fastened to the poles 1 and 1", respectively, but

are insulated therefrom by insulating blocks 19 and 22. The contact finger 18 co-operates with a conducting stud 17 attached to the upper side ofthe armature B to form a contact 17-18, and, in a similar manner, the contact finger 21 co-operates with a stud 20, also attached to the upper side of the armature B to form a contact 20-21.

The contact 17-18 controls the supply-of energy to winding 2 of electromagnet A; the

control circuit for winding 2, as here shown, passing from a battery 28 through wires 29 and 30, core 1 of electromagnet A, tube 13 which is of electrical conducting material, filament 3, armature B, contact 17-18, wire 31, winding 2 of electromagnet A, wire 31, a

v manually operable switch 32. and wire 33 back to battery 28. The contact 20-21 may be used for desired purpose. As illustrated in the drawings, this contact controls the supply of alternatin current to 'a air of line wires 34 and 35, t e former of w ich is connected directly with one terminal of an alternator G, and the latter of which is connected with the other terminal of alternator G, through contact 20-21, armature B, filament 3, tube 13, core lof electromagnet A, terminal post 37, and wires 30 and 36. a

, The operation of the apparatus is as follows: When switch 32 isopen, the parts occupy the positions in which they are shown in Figs. 1 and 2 so that contact 17-18 is closed. When switch 32 is closed, however,

I winding 2 of electromag'net A is supplied 'with current over the control circuit pre viously traced, and a magnetic flux is set up in jcore 1. This flux threads armature B, and since the armature tends to move to decrease the reluctance of the magnetic circuit in which it is included, armature B swings in a counterclockwise direction. When the-armature has swung through a predetermined 'distance, contact 17-18 opens and de-energizes electromagnet A, thus removing the orce tendin to deflect the armature' As soon as the klnetic energy. acquired by armature B during this clockwise rotation has been spent in deforming the filament 3 andthe spring 24, the otential energy which is then stored in the filament and the spring ro tates the armature inthe opposite or clockwise direction. Contact 17-18 then again becomes closed so that winding 2 of electromagnet A is again supplied with current. "As before, there is set up in core 1 a magnetic flux which threads armature B, but since armature B is now rotating in a clockwise direction, the magnetic pull which the flux exerts on the armature tends to decelerate the armature. Furthermore, as soon as the armature has rotated in this latter direction past the normal position to which it is biased by the filament 3, the spring 24, and the contact fingers 18 and 21, these members become deformed and also exert a force on the armature which opposes its clockwise rotation. As a result, when the armature has rotated in this clockwise direction to a position in which the kinetic en ergy acquired by the armature during this rotation is all spent in overcoming the above mentioned opposing forces, the armature stops rotating, whereupon. the energy stored in the elastic members and the magnetic pull exerted on the armature by the flux which threads the armature cause the armature 1 to again rotate in a counter-clockwise direc tion. It will be noted that, because of the inductance of winding 2, the current in winding 2 does not attain full value immediately upon the closing of contact 17-18, but has a greater value upon the opening of this contact, and for thls reason, the average magnetic force tending to decelerate armature B during its clockwise rotation is less assafaae than the average ma%ietic force tending to accelerate armature during its counterclockwise rotation. Armature B therefore quickly starts to oscillate with a fixed amphtude of oscillation, and continues to oscillate at this amplitude as long as switch 32 remains closed as will be readily understood.

It is desirable that armature B shall oscillate with simple harmonic motion because if this condition can be attained, the period of oscillation of the armature will be independent of the amplitude of oscillation, and henceof the applied voltage. In order to have the armature oscillate with simple harmonic motion it is necessary that the restoring force applied to the armature be proportional at all times to the displacement of the armature from its normal position. I therefore arrange the resilient members, that is, the filament 3, spring 24, and contact fingers 18 and 21, in such manner that when the armature occupies its normal position to which it is biased by these members, these members are all substantially unstressed. With the members arranged in this manner, the restoring force applied to the armature by the filament 3 and spring 24 will at all. times'be propertional to the displacement of the armature from its normal position up to the elastic limit of the materials, which is far above the stresses occurring invoperation. I also make the radius arm of the contact fingers 18 and 21 three or four times as long as the radius arm of the associated studs and I arrange the fingers in such manner that the fingers will just eng .gethe studs when the armature occupies its normal position. Furthermore, I attach the studs to the top of the armature in such positions that, when the armature has moved in one direction (the clockwise direction'with the apparatus shown in the drawings) to a point midway between the extremity of its stroke in this direction and its normal position, the studs will then be moving normal to the effective radius of the asso ciated contact fingers. "With the contact fingers arranged in this manner, it is evident that as the armature rotates from its normal position in a clockwise direction, the moment arm through which the restoring force of the fingers on the armature acts increasesuntil the armature reaches the mid-point referred to above. after which it again dc- :reases. At the same time the effective lengths of the fingers decrease and then increase, so that the stiffness of the fingers increases and then decreases. Furthermore. under these conditions, the shape of the fingers is constantly changing so that the direction in which the restoring force of the fingers on the armature acts is changing. It will be apparent. therefore. that if the restoring force exerted on the armature by the fingers at the start of the counter-clockwise rotation of the armature from its normal position is proporot its normal position, the increase of the restoring force of the fingers above proportionality with the displacement of the arma ture from its normal position, will not exceed 2%. Since the frequency of oscillation of the armature varies as the square root of the elastic forces. this deviation of the restoring force of the contact fingers from true proportionality with the displacement of the armature from its normal position would only cause an error of I -'\/2%:'- or 1.4%, in the frequency of oscillation even if the contact fingers exerted the whole rcstoring force. In practice, however, the restoring force of the fingers is only a small part of the total restoring force, so that the apparatus maintains a fixed frequency within much less than 1.4%.

In order that armature B shall oscillate with simple harmonic motion, it is further necessary that the driving force applied to the armature, that is, the magnetic pull exerted on the armature, should vary directly with the amplitude of oscillation of the armature. The energy stored in the armature at maximum amplitude varies as the square of the amplitude, but the dissipative losses, contact slide and core eddy currents also vary as the square of the amplitude. Hence, the power input varies as the square of the amplitude. The power input, however, also varies as the .square of the voltage, and since the constants of the electric circuit average-d over a cycle remain substantially unchanged with changes in amplitude of oscillation, it will be apparent that the amplitude of oscillation varies'as the applied voltage.

'I have discovered that in order for armature B to oscillate with simple harmonic motion, the changes in inductance of the electromagnet caused by changes in the reluctance of the magnetic circuit including the armature and the poles 1 and 1 during any complete oscillation of the armature should be ioo independent of the amplitude of oscillation x of the armature, or in other words, the

change in inductance should be the same for the minimum operating amplitude of the armature as for the maximum operating amplitude. This means that the changes in the an gaps between the armature and the pulse.

armature in the normal position should preferably be about tw ce that of the mini mum practicable from construction consideratibn at the point where. the contact 17-18 opens, so that a two to one change in inductance is obtained for the first driving These desirable features are obtained with the @armature shaped in the manner previously described in connection with Figs. 1, 2 and 3. With the armature constructed in'this manner, it will be apparent that a large starting torque is obtained, and at the same time practically the total change in inductance occurs within the minimum amplitude of oscillation, the limits of which are indicated by the dotted and full line positions of the armature in Fig. 3. The abrupt change in the contour of the armature due to the shoulders 9 and 9 increases the change in inductance which can be obtained with a small amplitude of oscillation and hence increases the operating eiiiciency.

It will he noted that the studs 13 and 14 are located close to the point about which the armature oscillates so that-good contact pressure is obtained between these studs and the associatcdcontact fingers without requiring a large torque to produce it. The advantage of this arrangement is that contact pressure adjustments have little effect on the frequency of oscillation.

While I have shown only two contacts it will be readily understood that more contacts may be provided if desired. If special arrangements of contactsproduce a departure from simple harmonic elastic forces, the armature may be made to oscillate with simple harmonic motion by shaping tie armature in such manner that the magnetic pull on the armature will vary with the position of the armature in a manner to compensate for the departure of the contacts from simple harmonic elastic forces. Thus, if. the frequency of oscillation of the armature decreases at large amplitudes. the frequency of oscillation may be made to increase to the I proper value by providing each of the proections 8 and 8 with outer surfaces which -slope toward the associated shoulders, 9" or 99with a gradual slope over a long are, as

best seen in Fig. 4. sothat the reluctance of the magnetic circuit including'the armature and the poles 1. and 1" will increase more gradually-than would be the case with the .poles 1 and 1", and hence the reluctance of the magnetic circuit'including the armature and the poles 1" and I will first decrease and then increase during a portion of each oscillation when the armature is oscillating with a large amplitude.

. The frequency of oscillation of armature '13 may be readily adjusted by varying the gage and length of spiral spring 24 which spring principally determines the period of the armature. It will be-noted that when the armature is oscillating, contact 20-21 interrupts the suppl of curernt to the line wires 34 and 35 at t 1e frequency of oscillation of the armature, so that these wires are supplied .with current which is periodically interrupted at this frequency. The wires 34 and 35 may be connected with any suitable apparatus. For exam )le, the wires 34 and 35 may be connected wit the track rails of a stretch of railway track in an automatic train control system for sup ilying periodically mterrupted current to t ese rails for controlling train carried governing apparatus. lVhcn used for this purpose the switch 32 would usually be controlled in accordance with trailic conditions in advance of the stretch.

Coding apparatus embodying my invention is very efiicient, the only material losses being a slight frictional loss due to contact slide, and an eddy current loss in the armature B largest for voltages greater than normal. The frictional loss due to contact slide is desirable because it keeps the contacts clean, while the loss due to eddy currents is does not require carefulleveling. is quickly 1 I self-starting, and has an extremely high frequency constancy.

Although I have herein shown and described only a few forms of coding apparatus embodying my invention, it is underfilament position, a contact controlled in accordance with the position of said armature, and a l have the appended claims without departing from the spirit and scope of my invention.

Having thusdescribed my invention, what I claim is:

1. Coding apparatus comprising a magnet having two poles, a filament, a cylindrical armature suspended by means of said filament to oscillate between said poles and having two projections one located adjacent each said ole, resilient means including said or biasing saidarmature to one winding for said magnet controlled by said contact.

2. Coding apparatus comprising a magnet having two poles, a. filament, a cylindrical armature suspended by means of said filament to oscillate between said poles and having two projections one located adjacent each said pole, a spiral spring, means including said filament and said spring for biasing said armature to one position, a Contact controlled in accordance with the position of said armature, nd a winding for said magnet controlled y said contact.

3. Coding apparatus comprising a magnet having two spaced poles,,a filament, an

armature suspended by means ofsaid filament to oscillate between said poles'and'having two projections one located adjacent each said pole, a resilient contact finger, a stud attached to said armature and co-acting with said contact finger, a spiral spring, means includin said filament, said spring, and said contact nger for biasing said'armature to one position, said projections being shaped in such manner that when said armature is rotated from said one position the reluctance of the magnetic circuit including said armature and said poles is increased or decreased depending upon the direction of such rotation, and a winding for said magnet controlled by said contact finger and said stud.

4. Coding apparatus comprising a filament having one end fixed, an armature suspended [from the other end of said filament and arranged to oscillate in a horizontal plane,.

said armature being provided with two symmetrical diametrically opposite projectlons, a stud attached to said armature, a resilient contact finger co-operating with said stud to form a contact, a spiral spring; means including said filament, said spring, and said contact finger for biasing said armature to one position, an electromagnet controlled by said contact and having its poles located one adjacent each said projection for oscillating saidarmature; the contour of said projection being "such that the torque exerted on said armature by said electromagnet when said armatureis rotated from said one position in one direction increases or decreases as'the -counter torque exerted on said armature by said filament, said contact finger, and said spring increases or decreases.

5. oding apparatuscomprising a magnet having two spaced poles and provided with an energizing winding, a filament having one end fixed in space, an armature suspended by means of said filament to oscillate between said poles andprovided with two symmetrical diametrically op osite projections each having a radially extending shoulder and each. having its outer surface substantially arcuate but having a portion of its surface adjacent the associated shoulder rounded more abruptly than the remainder of its outer surface, a stud attached to said armature, a resilient contact finger cooperating with said stud to form a contact, a-spiral sprin ,means including said contact finger, said filament, and said spring for biasing said armature to the position-in which said shoulders are located approximately at the centers of said pole pieces, and

a winding for said magnet controlled by said stud and said contact finger.

6. Coding apparatus comprising a magnet having a magnetizable core provided with an energizing winding and two poles, a filament having one end attached to said core, an armature suspended by means of said filament to oscillate between said poles and provided with two' projections each having'two radially extending shoulders and each having its outer surface curved in such manner that rotation of said armature from a predetermined position'decreases or increases the reluctance of said magnetic circuit according as said armature is rotated from said predetermined position in one direction or the other, a spiral spring, two studs attached to said armature, two contact fingers one coacting with each stud to form a contact and each arranged in such manner that the associated stud engages the fingers at all times except when said armature has been rotated through a predetermined distance from said predetermined position in one direction, means including said spiral spring, said filament and said contact fingers for biasing said armature to said predetermined position; and a winding for said magnet controlled by one of said contacts.

7. Coding apparatus comprising a magnet having two spaced poles, an armature biased to one position and mounted to oscillate as a torsion pendulum between said poles, said armature being shaped in such manner that when the armature is rotated from said one position the reluctance of the magnetic cirfor causing the magnet to oscillate said armature through at least a. minimum amplitude, the parts bein constructed in such manner that the tota change in the reluctance of said magnetic circuit occurs within the arc of said minimum am litude.

In testimony whereof I a x my'signature.

, PAUL N. BOSSART. 

